Internal documents published yesterday by the Washington Post detail the NSA's dream of building a quantum computer that can calculate information leaps and bounds faster than today's silicon chip machines, making it very useful for—among many other things—breaking even the most complex cryptographic locks.A traditional computer stores data in binary bits—a series of 1s and 0s. But a quantum computer uses quantum bits—qubits—that exist as 1s and 0s simultaneously and in various combinations, which is much more powerful. The tricky part is those qubits are temperamental as hell, and must be handled in extremely precise environments. So, to try and build the computer of the future, the NSA is leaning on some tried-and-true technology from the past.

According to the leaked documents, the agency carries out many of its quantum theory research in metal boxes that block out electromagnetic energy that could mess with the qubits. They’re called Faraday cages and were invented by Michael Faraday back in 1836. The idea is to control electricity to get just the right amount, but not too much. It’s a simple concept that enables many of the everyday conveniences we take for granted nowadays, like microwave ovens, not getting electrocuted when lightning strikes a plane, and elevators—that's why your cell phone signal cuts out between floors.

Faraday cages shield their contents from the electromagnetic field that surrounds a charged particle like an electron or proton. It works like a conductor that redistributes the electric charges to cancel out their effect on the interior and stay only around the exterior of the box. The shield often looks like a metallic mesh box—in the NSA's case, one the size of a full room.

There remains a physical, unavoidable limit in classical computing that is just the limit imposed by the size of electrons vs. the size of electrical components. ("Size" and electrons is a difficult idea, but let's just pretend for now it isn't.) Sooner or later, you hit a wall where past it, you can no longer control electrons sufficiently for computing.

This is where quantum computing comes in. Instead of using charge to transmit information, quantum information uses a different particle property: spin. Welcome to the world of spintronics. Spin is a highly unique property in that instead of just transmitting just either a 1 or a 0, it can do both at once in different combinations.

The problem is, if a qubit is disturbed even the slightest bit it will fall out of its spin state and revert back to a 1 or 0 property. It makes it very hard for scientists to measure or control the quantum bits without them lapsing back into regular old bits, since the tools for measuring the particles are governed by the same laws of physics controlling the quantum state being measured. This is where Faraday cages come in. The electromagnetic-secure boxes help make sure the conditions of the environment don't interfere with the particles' delicate quantum state.

The simple 19th century innovation plays a crucial role in the federal government's effort to win the quantum computing race. The NSA documents didn't say how close the agency is to achieving the difficult goal, but experts have predicted the next-gen supermachines could be reality within 10 years. And the government’s not the only one with a vested interest in this new level of computational power; many scientists are also working hard to harness quantum computing for breakthroughs in fields like health and artificial intelligence.

For its part, the NSA's ominously titled encryption-busting quantum computing operation, “Penetrating Hard Targets,” is racing to beat out similar government-sponsored research in Europe. It wants to be first. The NSA is worried, ironically, that if someone beats it to the punch they could spy on its sensitive information and leak secrets that could threaten national security, reported the Post. When it comes to eavesdropping on the digital world, apparently the agency can dish it out but can't take it.